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T1/E1

A digital transmission link with a capacity of 1,544 Mbps. In the US, this link is called T1. In Europe, it is called E1. See also megabits per second (Mbps).

TAPI

See Telephony Application Programming Interface (TAPI).

tapisrv.exe

A support-service application that provides an execution context for the TAPI dynamic-link library to carry out duties such as allocating memory or accessing data structures that have been swapped out to disk.

TDD

See Telecommunications Devices for the Deaf (TDD).

Telecommucations Devices for the Deaf (TDD)

A data device for the transmission of coded signals. Typically, the device is a simple computer terminal consisting of a keyboard, acoustic coupler, and display, and runs at 300 baud.

telephony

The science of transmitting voice, data, video, or image signals over a distance using technology that integrates computers with the telephone network.

Telephony Application Programming Interface (TAPI)

Set of functions that allows programming of telephone line-based devices in a device-independent manner, giving personal telephony to users. TAPI supports both speech and data transmission, allows for a variety of terminal devices, and supports complex connection types and call-management techniques such as conference calls, call waiting, and voice mail. TAPI allows all elements of telephone usage—from the simple dial-and-speak call to international e-mail—to be controlled within applications developed for the Microsoft® Win32® application programming interface (API). See the Microsoft Telephony Overview.

Telephony Service Provider Interface (TSPI)

Tool for creating service providers for the Microsoft Windows family of operating systems that support the Microsoft Win32 application programming interface (API). Win32 TSPI defines how the network shares information with Windows Telephony, which in turn talks to the API, which talks to the Windows Telephony applications. For additional information, see Telephony Service Provider Interface (TSPI).

third-party call control

A party call-control model that allows an application to establish or answer a call between any two parties.

threads

Individual processes within a single application.

tick count

The number of milliseconds since Windows started.

time to live (TTL)

A value in the range 0 through 255 that defines the scope within which multicast packets should be sent over a network using Internet Protocol (IP). The scope is defined in terms of how local or remote a packet's destination is. Each router decrements the TTL by one. When the value reaches a predefined lower limit, the router throws the packet away. Current multicast backbone (MBONE) requirements, available at the ftp://ftp.isi.edu/mbone/faq.txt site, define the following standard scopes: local network, 1; local site, 15; region, 63; world, 127. Other settings may have local meaning; for example, 31 might indicate all sites within a particular organization.

timestamp

An imprint of time/date created when a specific event or process takes place.

TSPI

See Telephony Service Provider Interface (TSPI).

TTL

See time to live (TTL).

twisted pair

Regular telephone wiring. Each telephone wire is actually a pair of wires.